I am not really a person who likes temples so much but I was absolutely amazed when I saw Angkor Wat. What a fantastic place and I would recommend everyone who is going to be near Cambodia to add Siem Reap and the Angkor temples to your to do list. Just incredible, awe-inspiring, spirit-lifting, mind-enhancing site.
We spent two and a half days here, which was about enough time. Don't save $$ on guide thinking that he can be replaced by guidebook. There are 101 things written in the book, but you only got time for 10 of them (unless you spend 1 month at Siam Reap), so you need a good guide to tell you which 10 are the most important among them.
We rose at 4am to catch the sunrise; and it was definitely worth it.....The grandeur of the place and looming towers is truly spectacular.
Start early before it is too hot. Take lots of water, wear good sensible shoes. You have to be mobile to manage the stairs...there are few hand rails, stairs are narrow. Especially at Bayon, you need to be sure footed.